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5 Rejuvenating Blood Factor TIMP2 Relates to Physical Activity and Cognitive Functioning in Older Adults on The Alzheimer’s Disease Continuum
- Emily W Paolillo, Shannon Y Lee, Anna M Vandebunte, Rowan Saloner, Leslie S Gaynor, Joel H Kramer, Kaitlin B Casaletto
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 106-107
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Objective:
Tissue inhibitor of metalloproteinases 2 (TIMP2) is produced peripherally, crosses the blood-brain barrier, and improves synaptic plasticity and hippocampal-dependent cognition in aged mice; however, the role of TIMP2 in human cognitive aging is unclear. We examined associations of circulating TIMP2 levels in blood with a known plasticity-inducing behavior, physical activity, and cognitive functioning among older adults along the Alzheimer’s disease continuum.
Participants and Methods:Participants included 84 community-dwelling older adults (meanage = 78.8; 57% female; 82% cognitively normal; 14% MCI; 4% mild dementia; 35% PET Aß+) enrolled in the UC San Francisco Memory and Aging Center. All participants completed 30 days of observational FitbitTM monitoring to quantify physical activity (average daily steps), as well as a comprehensive in-person visit including blood draw (proteins assayed on SOMAscan platform), [18F]AV-45 positron emission tomography (PET) to quantify brain beta-amyloid (centiloids), and neuropsychological assessment. Composite cognitive z-scores were calculated for memory (California Verbal Learning Test-II [CVLT-II] and Benson Figure Recall), semantic processing (animal fluency and Boston Naming Test), and executive functioning (digits backwards span, Stroop inhibition, modified trail making test, lexical fluency, and design fluency). Multiple linear regression examined TIMP2 as a function of physical activity, covarying for age and PET centiloids. Additional regression models separately examined cognitive z-scores as a function of TIMP2, covarying for age, sex, education, PET centiloids, and body mass index (BMI).
Results:TIMP2 was not significantly correlated with age, sex, education, or PET centiloids (ps > 0.05); however, TIMP2 was negatively correlated with BMI (r = -0.23, p = 0.036). Greater average daily steps related to higher levels of TIMP2 (b = 0.30, 95%CI = 0.04-0.55, p = 0.022). TIMP2 also related to better semantic processing (b = 0.28, 95%CI = 0.04-0.51, p = 0.021) and executive functioning (b = 0.26, 95%CI = 0.03-0.49, p = 0.028). TIMP2 did not significantly relate to memory (p > 0.05).
Conclusions:Greater physical activity was associated with higher concentrations of blood factor TIMP2, which in turn related to better cognitive functioning independent of Alzheimer’s disease pathology burden. These results support previous mouse models by broadly replicating relationships between TIMP2 and cognition in humans, while also uniquely demonstrating an association between TIMP2 and physical activity, a modifiable protective factor in both typical and diseased cognitive aging. Our domain-specific results, however, suggest that benefits of TIMP2 in humans may involve a broader neuroanatomical network than the hippocampal-specific effects previously shown in mice. Although exact mechanisms of TIMP2 need further examination, TIMP2 is known to be enriched in human umbilical cord plasma, has been shown to be involved in cell-growth promoting activities, and may relate to increased neural plasticity in older age. Further examination of TIMP2 and other novel blood-based proteins as potential therapeutic targets for improved cognitive aging, including in the presence of Alzheimer’s disease, is warranted.
6 The Moderating Role of Physical Activity on Hippocampal Iron Deposition and Memory Outcomes in Typically Aging Older Adults
- Shannon Y Lee, Emily W Paolillo, Rowan Saloner, Torie Tsuei, Anna VandeBunte, Joel H Kramer, Kaitlin B Casaletto
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 794-795
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Quantitative Susceptibility Mapping (QSM) is an MRI-based technique that sensitively measures in-vivo iron deposition via relaxation and magnetic susceptibility of brain tissue. Iron is essential for brain homeostasis, including oxidative metabolism, formation and maintenance of neural networks, and myelin synthesis. While increased levels of iron deposition occur during normal aging, high levels may have detrimental effects. Previous work has linked excessive brain iron accumulation to oxidative stress, beta-amyloid and tau toxicity, neurodegeneration, and cognitive dysfunction, particularly memory loss. Physical activity, on the other hand, correlates with higher synaptic integrity and memory performance, even in the presence of neuropathology. To date, it is unknown how physical activity may affect iron deposition-related cognition changes. We examined the moderating role of physical activity on the relationship between QSM hippocampal iron deposition and verbal memory in typically aging adults.
Participants and Methods:62 cognitively unimpaired older adults from the UCSF Memory and Aging Center (age mean(SD) = 78.34(7.28) years; 56% women; education mean(SD) = 17.94(1.72) years; 85% non-Hispanic White) completed neuropsychological testing and brain MRI during annual research visits, followed by Fitbit™ physical activity monitoring for 30 days. Average total daily steps were aggregated. Participants completed 3T Prisma neuroimaging with QSM, and regional iron deposition levels were quantified. All subjects also underwent diffusion tensor imaging (fractional anisotropy). Verbal memory was assessed via long delay free recall scores from the California Verbal Learning Test II (CVLT-II). Linear regression examined verbal memory as a function of hippocampal QSM (bilateral), physical activity, and their interaction. Models covaried for age, sex, and education. Additional models separately examined left and right hippocampal QSM, as well as subcortical QSM to determine lateralization and specificity of verbal memory effects to hippocampal iron deposition, respectively.
Results:Univariably, higher bilateral hippocampal QSM correlated with worse verbal memory (r= 0.35; p= 0.015). Adjusting for demographics, physical activity moderated the relationship between bilateral hippocampal QSM and verbal memory (ß= 0.41, p= 0.011), such that at higher levels of physical activity, the negative relationship between hippocampal QSM and verbal memory was significantly attenuated. Results persisted when adjusting for DTI integrity of the uncinate fasciculus and fornix white matter tracts. Lateralization models were both significant, suggesting that results were not dominantly driven by either left (ß= 0.34, p= 0.048), or right (ß=0.31, p= 0.035) hippocampal QSM. In contrast, subcortical QSM did not correlate with memory performance (r= 0.13, p > 0.05) or interact with physical activity on verbal memory outcomes (p > 0.05).
Conclusions:Physical activity significantly moderated the negative relationship between hippocampal QSM and verbal memory performance. Higher exercise engagement may buffer the adverse effect of hippocampal iron deposition on memory, potentially through its role in maintenance of myelin and synaptic integrity and/or protecting against other neurotoxic events (e.g., oxidative stress, neuronal cell death). Our results support that physical activity continues to be a modifiable risk factor that may offer a protective role in neurobiological pathways of memory and cognitive decline.
73 Sex Differences in Verbal Memory and Alzheimer’s Disease Biomarkers in Clinically Normal Older Adults: Role of SNAP-25 Genetics
- Rowan Saloner, Emily W Paolillo, Kevin J Wojta, Corrina Fonseca, Eva Q Gontrum, Argentina Lario-Lago, Gil D Rabinovici, Jennifer S Yokoyama, Jessica E Rexach, Joel H Kramer, Kaitlin B Casaletto
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 377-378
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Objective:
Females outperform males on verbal memory tests across the lifespan. Females also exhibit greater Alzheimer’s disease (AD) pathology at preclinical stages and faster atrophy and memory decline during disease progression. Synaptic factors influence the accumulation of AD proteins and may underpin cognitive resilience against AD, though their role in sex-related cognitive and brain aging is unknown. We tested interactive effects of sex and genetic variation in SNAP-25, which encodes a presynaptic protein that is dysregulated in AD, on cognition and AD-related biomarkers in cognitively unimpaired older adults.
Participants and Methods:Participants included a discovery cohort of 311 cognitively unimpaired older adults (age mean [range]=70 [44-100]; 56% female; education mean=17.3 years; 24% APOE-e4+), and an independent, demographically-comparable replication cohort of 82 cognitively unimpaired older adults. All participants completed neurological examination, informant interview (CDR=0), neuropsychological testing, and blood draw. Participants were genotyped for the SNAP-25 rs105132 (T→C) single-nucleotide polymorphism via Sequenom (discovery cohort) or Omni 2.5M (replication cohort). In vitro models show the C-allele is associated with increased SNAP-25 expression compared to T/T genotype. A subset of the discovery cohort completed structural MRI (n=237) and florbetapir Aβ-PET (n=97). Regression analyses across cohorts examined the interaction of sex and SNAP-25 genotype (T/T homozygotes [53% prevalence] vs. C-carriers [47% prevalence]) on cognitive z-scores (verbal memory, visual memory, executive function, language), adjusting for age, education, APOE-e4, and APOE-e4 x sex. Discovery cohort models also examined sex-dependent effects of SNAP-25 on temporal lobe volumes and Aβ-PET positivity.
Results:SNAP-25 T/T vs. C-carriers did not differ on demographics or APOE-e4 status across cohorts or within sexes. Sex interacted with SNAP-25 to predict verbal memory (p=.024) and language (p=.008) in the discovery cohort, with similar verbal memory differences observed in the replication cohort. In sex-stratified analyses, C-carriers exhibited better verbal memory than T/T carriers among females (d range: 0.41 to 0.64, p range: .008 to .046), but not males (d range: 0.03 to 0.12, p range: .499 to .924). In SNAP-25-stratified analyses, female verbal memory advantages were larger among C-carriers (d range: 0.74 to 0.89, p range: <.001 to .034) than T/T (d range: 0.13 to 0.36, p range: .022 to .682). Sex also interacted with SNAP-25 to predict Aβ-PET positivity (p=.046) such that female C-carriers exhibited the lowest prevalence of Aβ-PET positivity (13%) compared to other groups (23% to 35%). C-carriers exhibited larger temporal lobe volumes across sex, yet this effect only reached statistical significance among females (females: d=0.41, p=.018; males: d=0.26, p=.179). In post-hoc analyses, larger temporal lobe volumes were selectively associated with better verbal memory in female C-carriers (β=0.36, p=.026; other groups: |βs|<0.10, ps>.538).
Conclusions:Among clinically normal older adults, we demonstrate female-specific advantages of carrying the SNAP-25 rs105132 C-allele across cognitive, neural, and molecular markers of AD. The rs105132 C-allele putatively reflects higher endogenous levels of SNAP-25. Our findings suggest a female-specific pathway of cognitive and neural resistance, whereby higher genetically-driven expression of SNAP-25 may reduce likelihood of amyloid plaque formation and support verbal memory, possibly through fortification of temporal lobe structure.
Binge Drinking Relates to Worse Neurocognitive Functioning Among Adults Aging with HIV
- Emily W. Paolillo, Rowan Saloner, Maulika Kohli, C. Wei-Ming Watson, Raeanne C. Moore, Robert K. Heaton, David J. Moore
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- Journal of the International Neuropsychological Society / Volume 28 / Issue 6 / July 2022
- Published online by Cambridge University Press:
- 26 July 2021, pp. 600-610
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Given the aging population of people with HIV (PWH), along with increasing rates of binge drinking among both PWH and the general older adult population, this study examined the independent and interactive effects of HIV, binge drinking, and age on neurocognition.
Method:Participants were 146 drinkers stratified by HIV and binge drinking status (i.e., ≥4 drinks for women and ≥5 drinks for men within approximately 2 h): HIV+/Binge+ (n = 30), HIV−/Binge+ (n = 23), HIV+/Binge− (n = 55), HIV−/Binge− (n = 38). All participants completed a comprehensive neuropsychological battery measuring demographically-corrected global and domain-specific neurocognitive T scores. ANCOVA models examined independent and interactive effects of HIV and binge drinking on neurocognitive outcomes, adjusting for overall alcohol consumption, lifetime substance use, sex, and age. Subsequent multiple linear regressions examined whether HIV/Binge group moderated the relationship between age and neurocognition.
Results:HIV+/Binge+ participants had worse global neurocognition, processing speed, delayed recall, and working memory than HIV−/Binge− participants (p’s < .05). While there were significant main effects of HIV and binge drinking, their interaction did not predict any of those neurocognitive outcomes (p’s > .05). Significant interactions between age and HIV/Binge group showed that HIV+/Binge+ participants demonstrated steeper negative relationships between age and neurocognitive outcomes of learning, delayed recall, and motor skills compared to HIV−/Binge− participants (p’s < .05).
Conclusions:Results showed adverse additive effects of HIV and binge drinking on neurocognitive functioning, with older adults demonstrating the most vulnerability to these effects. Findings support the need for interventions to reduce binge drinking, especially among older PWH.
Use of Neuroimaging to Inform Optimal Neurocognitive Criteria for Detecting HIV-Associated Brain Abnormalities
- Laura M. Campbell, Christine Fennema-Notestine, Rowan Saloner, Mariam Hussain, Anna Chen, Donald Franklin, Jr., Anya Umlauf, Ronald J. Ellis, Ann C. Collier, Christina M. Marra, David B. Clifford, Benjamin B. Gelman, Ned Sacktor, Susan Morgello, J. Allen McCutchan, Scott Letendre, Igor Grant, Robert K. Heaton, for the CHARTER Group
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- Journal of the International Neuropsychological Society / Volume 26 / Issue 2 / February 2020
- Published online by Cambridge University Press:
- 02 October 2019, pp. 147-162
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Frascati international research criteria for HIV-associated neurocognitive disorders (HAND) are controversial; some investigators have argued that Frascati criteria are too liberal, resulting in a high false positive rate. Meyer et al. recommended more conservative revisions to HAND criteria, including exploring other commonly used methodologies for neurocognitive impairment (NCI) in HIV including the global deficit score (GDS). This study compares NCI classifications by Frascati, Meyer, and GDS methods, in relation to neuroimaging markers of brain integrity in HIV.
Method:Two hundred forty-one people living with HIV (PLWH) without current substance use disorder or severe (confounding) comorbid conditions underwent comprehensive neurocognitive testing and brain structural magnetic resonance imaging and magnetic resonance spectroscopy. Participants were classified using Frascati criteria versus Meyer criteria: concordant unimpaired [Frascati(Un)/Meyer(Un)], concordant impaired [Frascati(Imp)/Meyer(Imp)], or discordant [Frascati(Imp)/Meyer(Un)] which were impaired via Frascati criteria but unimpaired via Meyer criteria. To investigate the GDS versus Meyer criteria, the same groupings were utilized using GDS criteria instead of Frascati criteria.
Results:When examining Frascati versus Meyer criteria, discordant Frascati(Imp)/Meyer(Un) individuals had less cortical gray matter, greater sulcal cerebrospinal fluid volume, and greater evidence of neuroinflammation (i.e., choline) than concordant Frascati(Un)/Meyer(Un) individuals. GDS versus Meyer comparisons indicated that discordant GDS(Imp)/Meyer(Un) individuals had less cortical gray matter and lower levels of energy metabolism (i.e., creatine) than concordant GDS(Un)/Meyer(Un) individuals. In both sets of analyses, the discordant group did not differ from the concordant impaired group on any neuroimaging measure.
Conclusions:The Meyer criteria failed to capture a substantial portion of PLWH with brain abnormalities. These findings support continued use of Frascati or GDS criteria to detect HIV-associated CNS dysfunction.
Conditional Effects of Lifetime Alcohol Consumption on Methamphetamine-Associated Neurocognitive Performance
- Rowan Saloner, Emily W. Paolillo, Anya Umlauf, David J. Moore, Robert K. Heaton, Igor Grant, Mariana Cherner, The TMARC Group
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- Journal of the International Neuropsychological Society / Volume 25 / Issue 8 / September 2019
- Published online by Cambridge University Press:
- 10 June 2019, pp. 787-799
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Methamphetamine (MA) dependence contributes to neurotoxicity and neurocognitive deficits. Although combined alcohol and MA misuse is common, how alcohol consumption relates to neurocognitive performance among MA users remains unclear. We hypothesized that alcohol and MA use would synergistically diminish neurocognitive functioning, such that greater reported alcohol consumption would exert larger negative effects on neurocognition among MA-dependent individuals compared to MA-nonusing persons.
Methods:Eighty-seven MA-dependent (MA+) and 114 MA-nonusing (MA−) adults underwent neuropsychological and substance use assessments. Linear and logistic regressions examined the interaction between MA status and lifetime average drinks per drinking day on demographically corrected global neurocognitive T scores and impairment rates, controlling for recent alcohol use, lifetime cannabis use, WRAT reading performance, and lifetime depression.
Results:MA+ displayed moderately higher rates of impairment and lower T scores compared to MA−. Lifetime alcohol use significantly interacted with MA status to predict global impairment (ORR = 0.70, p = .003) such that greater lifetime alcohol use increased likelihood of impairment in MA−, but decreased likelihood of impairment in MA+. Greater lifetime alcohol use predicted poorer global T scores among MA− (b = −0.44, p = .030) but not MA+ (b = 0.08, p = .586).
Conclusions:Contrary to expectations, greater lifetime alcohol use related to reduced risk of neurocognitive impairment among MA users. Findings are supported by prior research identifying neurobiological mechanisms by which alcohol may attenuate stimulant-driven vasoconstriction and brain thermotoxicity. Replication and examination of neurophysiologic mechanisms underlying alcohol use in the context of MA dependence are warranted to elucidate whether alcohol confers a degree of neuroprotection.
Neurocognitive SuperAging in Older Adults Living With HIV: Demographic, Neuromedical and Everyday Functioning Correlates
- Rowan Saloner, Laura M. Campbell, Vanessa Serrano, Jessica L. Montoya, Elizabeth Pasipanodya, Emily W. Paolillo, Donald Franklin, Ronald J. Ellis, Scott L. Letendre, Ann C. Collier, David B. Clifford, Benjamin B. Gelman, Christina M. Marra, J. Allen McCutchan, Susan Morgello, Ned Sacktor, Dilip V. Jeste, Igor Grant, Robert K. Heaton, David J. Moore, the CHARTER and HNRP Groups
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- Journal of the International Neuropsychological Society / Volume 25 / Issue 5 / May 2019
- Published online by Cambridge University Press:
- 20 March 2019, pp. 507-519
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Objectives: Studies of neurocognitively elite older adults, termed SuperAgers, have identified clinical predictors and neurobiological indicators of resilience against age-related neurocognitive decline. Despite rising rates of older persons living with HIV (PLWH), SuperAging (SA) in PLWH remains undefined. We aimed to establish neuropsychological criteria for SA in PLWH and examined clinically relevant correlates of SA. Methods: 734 PLWH and 123 HIV-uninfected participants between 50 and 64 years of age underwent neuropsychological and neuromedical evaluations. SA was defined as demographically corrected (i.e., sex, race/ethnicity, education) global neurocognitive performance within normal range for 25-year-olds. Remaining participants were labeled cognitively normal (CN) or impaired (CI) based on actual age. Chi-square and analysis of variance tests examined HIV group differences on neurocognitive status and demographics. Within PLWH, neurocognitive status differences were tested on HIV disease characteristics, medical comorbidities, and everyday functioning. Multinomial logistic regression explored independent predictors of neurocognitive status. Results: Neurocognitive status rates and demographic characteristics differed between PLWH (SA=17%; CN=38%; CI=45%) and HIV-uninfected participants (SA=35%; CN=55%; CI=11%). In PLWH, neurocognitive groups were comparable on demographic and HIV disease characteristics. Younger age, higher verbal IQ, absence of diabetes, fewer depressive symptoms, and lifetime cannabis use disorder increased likelihood of SA. SA reported increased independence in everyday functioning, employment, and health-related quality of life than non-SA. Conclusions: Despite combined neurological risk of aging and HIV, youthful neurocognitive performance is possible for older PLWH. SA relates to improved real-world functioning and may be better explained by cognitive reserve and maintenance of cardiometabolic and mental health than HIV disease severity. Future research investigating biomarker and lifestyle (e.g., physical activity) correlates of SA may help identify modifiable neuroprotective factors against HIV-related neurobiological aging. (JINS, 2019, 25, 507–519)
HIV-Associated Neurocognitive Disorders: A Global Perspective
- Rowan Saloner, Lucette A. Cysique
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- Journal of the International Neuropsychological Society / Volume 23 / Issue 9-10 / October 2017
- Published online by Cambridge University Press:
- 04 December 2017, pp. 860-869
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The present review on HIV-associated neurocognitive disorders (HAND) provides a worldwide overview of studies that have investigated the rate and neuropsychological (NP) profile of HAND research since the inception of the 2007 HAND diagnostic nomenclature. In the first part, the review highlights some of the current controversies around HAND prevalence rates. In the second part, the review critically assesses some solutions to move the field forward. In the third part, we present the cross-sectional NP profile in non-Western HIV+ cohorts and in relation to Western cohorts’ findings. The adopted global perspective highlights the successful expansion of NP studies in HIV infection to culturally diverse low- to medium-income countries with high HIV burden. These studies have produced interestingly similar rates of HAND whether patients were naïve or treated and/or virally suppressed compared to the rich income countries where the NP research in NeuroHIV has originated. The perspective also demonstrates that globally, the group which is the most representative of the HIV epidemic, and thus at risk for HAND are persons with chronic HIV infection and survivors of past immunosuppression, while in relative terms, those who have been treated early with long-term viral suppression represent a minority. In the last part, we present a review of the naturalistic longitudinal NP global studies in HIV+cohorts, discuss the role of longitudinal design in solving issues around the question of asymptomatic neurocognitive impairment, and the question of biomarker discovery. Finally, we conclude by calling for greater methods and data harmonization at a global level. (JINS, 2017, 23, 860–869)